Add the Twitter datasource node to the canvas (red arrow). From the properties panel select the required server, and click Add Select Node.
Click the Select node on the canvas, and from the Properties Panel, set:
Resulting Table Name: name the given table (blue arrow).
Search: enter the required search term (green arrow). This may be a hashtag or a user handle. Results will be returned according to the search term entered.
Click Apply - the preview panel will open, displaying a preview of the table. Continue building the ETL as usual.